Something sublime was in the air. Was it the heatwave? The Ashes? A victory in the Tour de France? The economic recovery?

Or perhaps an indefinable feeling that, somehow, we’d moved to a more comfortable place in the affairs of man, a place that stands above the doings of governments and the FTSE 100?

It might have been a combination of all the above. But when the news finally broke last night it became clear that a large part of our sudden feelgood factor had to be ascribed to the Duchess of Cambridge and her ability to do something that, let’s face it, 740,000 other mothers in this country have already done in the past year.

A few of those thousands may wonder why this particular birth will be singled out for street parties, raucous rejoicing, and even calls for a public holiday when theirs was not.

But a royal birth is a moment for pause and reflection – and never more so than today.

The prospect now of a future king, preceded by another king, preceded by another king, is a fairly hefty concept to swallow when we as a nation have basked in a 60-year period when monarchy equalled matriarchy. Not only have we become accustomed to her face, we’ve learnt to adore our Queen and her enigmatic diplomacy: and the idea of switching to someone harder and more pro- active – as Charles’s harsher critics suggest – fidgeting on the throne while ministers fail to understand him, will take some getting used to. Hands up all those who were secretly hoping that Kate had a girl first.

But however this little boy turns out, we will learn to love him. We always do.

The compact between the Royal family and those it serves is elusive, indefinable. We like them one minute, loathe them the next. We praise them and we carp.

When they err and stray like lost sheep, no ordinance invented could make us adore them, simply because there’s an addition to the ranks.

This week, however, has put the seal on the return of a lost lustre, with a new sense of ease between Palace and people. It has to do with Kate and William, of course, and their serenely no-nonsense way of being royal. But there are other powerful factors at play as well.

The level of interest and excitement at the arrival of this baby is unparalleled in recent history. For those of us with long memories it certainly surpassed the thrill at the birth of Prince William 31 years ago.

It comes on the back of a joyously successful royal wedding, and, even more importantly, the Queen’s Diamond Jubilee. And notwithstanding the prevailing interest in our new princeling, at the heart of the recovery in the House of Windsor’s fortunes, the recovery which has brought us to where we are today, flags in hand, is the Queen herself.

The Duke and Duchess of Cambridge yesterday created a link to the future, a future which few of us will live to see. That is the USP of monarchy: its continuity onwards on a path which stretches over the horizon. A newborn child helps to eradicate further those small reservations which bother some perhaps more than they should.

There have been dark moments in recent Windsor history. Not just adulterous affairs, broken marriages and a tragic death that split the nation, but more fundamental matters to do with privilege, interference in the body politic and unchallenged wealth. Taken separately these issues amount to no more than minor irritations, which supporters of the Royal family can put down to jealousy, spite, and the wilful mischief of the tabloid press. But added together, they are greater than the sum of their parts. Whatever rope they were handed by their subjects, it sometimes appeared that certain members of the Royal family were in danger of running out of it.

But then – along came Kate. And if old-style courtiers blanched when they uncovered the Duchess’s patchwork ancestry, her future husband did not.

That some of Kate’s people were coal miners and labourers mattered nothing to him; and gradually the shift began, a shift which saw its genesis in the change of courtiers presenting this youngest rank of royals to the outside world – a new breed of men and women who saw how royalty could be made relevant for the 21st century.

Kate has brought new blood to the family, and the fact that her child’s great-great-great-grandfather John Goldsmith was a navvy, was a relief not a burden to the royal redesign (don’t forget that on the other side, another three-times grandfather was George V, Rex Imperator, sovereign of half the world).

On top of that it is clear that William adores his wife’s essentially middle-class family. At a stroke he has demolished the belief that royals really mix happily only with other royals or other aristocrats.

The couple cultivated a more “ordinary” vision of royalty while still remaining resolutely royal. In this they have been hugely helped by the bad-boy, good-boy antics of Prince Harry to whom they are both incredibly close. To serve your country bravely and with distinction, while at the same time making a complete idiot of yourself in Las Vegas takes some doing, but then Harry is some special kind of man — with colossal appeal to the younger generation.

Together, these three young people are reigniting and reinventing the golden days of royalty. None of this could have been achieved, however, without the stabilising presence of the Queen, whose popularity, if it continues on its present course, will shortly break all thermometers.

Her emergence from the days of annus horribilis has been nothing short of a joy to witness. She was 87 in April, yet her style and her smile have never been more assured, never more exuberant. She is truly at the top of her game.

Inevitably, there will be pitfalls ahead. For too long, those whose children married into the Royal family were outlaws, not in-laws — families were cautiously welcomed then sidelined. Prince William has made it clear this will not happen to the Middletons. No more telling indicator as to the success of this campaign will come with the choice of names for the royal baby.

Can William shoehorn in some Middleton names when the time comes to fill out the birth certificate? The family is peppered with deliciously non-royal handles including Ron, Steve, Tom, Gary and Fred.

We shall see. What is beyond doubt is that the birth of this baby coincides with the rebirth of the House of Windsor — cause for a double celebration all round.